Articles | Volume 12
Sci. Dril., 12, 32–45, 2011
Sci. Dril., 12, 32–45, 2011

  01 Sep 2011

01 Sep 2011

IODP Expedition 325: Great Barrier Reefs Reveals Past Sea-Level, Climate and Environmental Changes Since the Last Ice Age

Y. Yokoyama1, J. M. Webster2, C. Cotterill3, J. C. Braga4, L. Jovane5, H. Mills6, S. Morgan7, A. Suzuki8, and the IODP Expedition 325 Scientists Y. Yokoyama et al.
  • 1Atmosphere and Ocean Research Institute, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564 Japan
  • 2Geocoastal Reseach Group, School of Geosciences, The University of Sydney, Sydney, NSW 2006, Australia
  • 3British Geological Survey, Murchison House, Edinburgh, Scotland, EH9 3LA, UK
  • 4Departamento de Estratigrafia y Paleontologia, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva, 18002 Granada, Spain
  • 5Geology Department, Western Washington University, 516 High Street, MS 908, Bellingham, WA 98225, USA
  • 6Department of Oceanography, Texas A&M University, 716A Eller, O&M Building, College Station, TX 77843, USA
  • 7University of Leicester, Department of Geology, University Road, Leicester, LE1 7RH, UK
  • 8Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 7, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8567, Japan

Abstract. The timing and courses of deglaciations are key components in understanding the global climate system. Cyclic changes in global climate have occurred, with growth and decay of high latitude ice sheets, for the last two million years. It is believed that these fluctuations are mainly controlled by periodic changes to incoming solar radiation due to the changes in Earth’s orbit around the sun. However, not all climate variations can be explained by this process, and there is the growing awareness of the important role of internal climate feedback mechanisms. Understanding the nature of these feedbacks with regard to the timing of abrupt global sea-level and climate changes is of prime importance. The tropical ocean is one of the major components of the feedback system, and hence reconstructions of temporal variations in sea-surface conditions will greatly improve our understanding of the climate system. The Integrated Ocean Drilling Program (IODP) Expedition 325 drilled 34 holes across 17 sites in the Great Barrier Reef, Australia to recover fossil coral reef deposits. The main aim of the expedition was to understand the environmental changes that occurred during the last ice age and subsequent deglaciation, and more specifically (1) establish the course of sea-level change, (2) reconstruct the oceanographic conditions, and (3) determine the response of the reef to these changes. We recovered coral reef deposits from water depths down to 126 m that ranged in age from 9,000 years to older than 30,000 years ago. Given that the interval of the dated materials covers several paleoclimatologically important events, including the Last Glacial Maximum, we expect that ongoing scientific analyses will fulfill the objectives of the expedition.